Mat 18, 1906.] 



SCIENCE. 



789 



MAGNETISM OF DIAMOND DRILL RODS. 



The fourth report of the Michigan Acad- 

 emy of Science, 1904, contains a short paper 

 by Dr. A. C. Lane on ' Magnetic Phenomena 

 around Deep Borings,' in which attention is 

 called to the magnetism of iron or steel 

 casings in deep wells due to their position in 

 the earth's magnetic field. Cases were re- 

 ferred to in which the magnetism was suffi- 

 ciently strong to hold large-sized spikes or 

 even heavier wrenches, while difficulty was ex- 

 perienced in lowering heavily weighted steel 

 tapes into the wells, the tape being attracted 

 and held against the side of the casing. 



An instance has recently come under my 

 observation in which it appears that diamond 

 drill rods have become quite strongly mag- 

 netized because of their position in the earth's 

 magnetic field. Wbile prospecting for bodies 

 of magnetite in a basic hornblende-chlorite 

 schist enclosed on either side by more acid 

 rocks, the drillers found that the drill rods 

 became strongly magnetic. They attributed 

 the phenomenon to the influence of nearby 

 ore bodies, and one mining engineer, in report- 

 ing on the property, referred to the observed 

 magnetic effects as a conclusive proof of the 

 proximity of large bodies of magnetite in 

 depth. At the time the magnetism was 

 noticed and reported the drill was cutting 

 through the acid series of rocks, practically 

 free from magnetite. Similar effects were 

 reported from two different borings, but not 

 from other borings near by. 



Both of the drill-holes referred to are in- 

 clined several degrees from the vertical toward 

 the north, thus approaching parallelism with 

 the lines of force of the earth's magnetic field. 

 As is well known, an iron bar held in this 

 position becomes more strongly magnetic than 

 when held in an east-and-west line. It seemed 

 to me, therefore, that the conditions in the 

 case of the drill rods were especially favorable 

 for the production of strong magnetic effects. 

 According to the reports of several witnesses 

 the drill rods would hold heavy spikes, while 

 the pull on heavier masses of iron was very 

 noticeable. I did not observe the phenomena 

 myself, the holes in question having been 



abandoned and a new one commenced at the 

 time of my visit. D. W. Johnson. 



; SPECIAL ARTICLES. 



THE TERMINOLOGY OF THE PARTS OF THE GRASS 

 SPIKELET. 



Perhaps in no group of plants has there 

 been more variation in the use of terms than 

 in the use of those employed in botanical de- 

 scriptions of the grass spikelet. This multi- 

 plicity of terms and the resultant confusion 

 have been largely, but not altogether, the re- 

 sult of confused morphology. This has been 

 ably discussed by Bentham and his conclu- 

 sions, as to both morphology and terminology, 

 have been widely adopted. Of late years there 

 has been more or less tendency to discard 

 Bentham's terms in favor of others. This 

 has led the writer to investigate the whole 

 matter with the end in view of adopting the 

 terminology which best serves the purposes of 

 description. 



Using as a starting-point such a spikelet as 

 that of Bromus and the terminology of Ben- 

 tham, we have first the two empty glumes at 

 the base of the spikelet. The remainder of 

 the spikelet consists of distichous lateral 

 florets. Each floret has a large outer scale 

 or flowering glume. Opposite and above this 

 is the two-nerved palet. Opposite and above 

 the palet are the two delicate lodicules. Still 

 above these are the reproductive organs, the 

 whorl of three stamens and the pistil. 



Important modifications from this typical 

 form of spikelet occur as follows: 



The empty glumes may be entirely absent, 

 as in GoleanthiLS, solitary as in Nardus, mere 

 rudiments as in Eomalocenchrus and Zizania; 

 or the lateral spikelets may each have but one 

 empty glume, while the terminal has two as 

 in Monerma. In Uniola and the Bambusese 

 there are from three to six so-called empty 

 glumes. These are most probably sterile 

 flowering glumes and not proper empty glumes. 

 Such is clearly the case in the so-called third 

 empty glume of the Panicese, which often en- 

 closes more or less rudimentary sexual organs. 

 It is likewise very common for the terminal 

 florets in the Festucese to be reduced to an 



